The present invention relates to the analysis of acid-soluble aluminum in a steel sample and particularly an analyzer and etching charge measurement system used for determining the acid-soluble aluminum content.
During the manufacturing of steel, it is desirable to monitor the aluminum content of the steel and particularly the acid-soluble aluminum content. A variety of prior techniques have been proposed including a system of electrolytically etching a sample as disclosed in U.S. Pat. No. 4,533,642, issued to J. Kelly on Aug. 6, 1985. In electro-chemical systems, the weight of a sample in solution can be accurately determined by electrolytically etching a sample with a known quantity of charge according to Faraday's Law. In the implementation of this system, a constant current source is coupled to etching electrodes for a predetermined time. It is assumed that the current remains constant with time during etching for estimating the charge applied to the specimen. The difficulty with this system is that the actual charge is not measured, and the current can vary with temperature of electrolyte, sample type and its surface characteristics. Thus, the weight of material etched is only predicted. Further, the equipment employed in this system requires the utilization of a peristaltic pump for the movement of the etching solution and reagents involved in the process. This construction requires a debubbling chamber to eliminate gas bubbles from the chemical mixture before being analyzed by a spectral photometer.